Various devices and methods for stabilizing bone structures have been used for many years. For example, the fracture of an elongated bone, such as a femur or humerus, can be stabilized by securing a plate to the fractured bone across the fracture. The plate extends across the fractured area and thus stabilizes the fractured components of the bones relative to one another in a desired position. When the fracture heals, the plate can be removed or left in place, depending on the type of plate that is used.
Another type of stabilization technique uses one or more elongated rods extending between components of a bony structure and secured to the bony structure to stabilize the components relative to one another. The components of the bony structure are exposed and one or more bone engaging fasteners are placed into each component. The elongated rod is then secured to the bone engaging fasteners in order to stabilize the components of the bony structure. If one or more of the vertebrae are displaced as a result of spondylolisthesis or other deformity, correction is obtained by pulling the displaced vertebrae into alignment with the adjacent vertebrae prior to securing the rod to the vertebrae.
In these techniques access to the surgical site can be provided by cutting, removing, and/or repositioning skin, tissue and vasculature. This provides the surgeon access to the location where the stabilization device is to be installed, and accommodates placement of instruments to reduce vertebral displacement and to install the stabilization structures. There remains a need for instruments and methods for stabilizing bony structures that allow invasiveness to be reduced.